On the basis of examples mainly taken from Joseph Caspi's, Sarsot ha-kesef, this study tries to analyse how this rationalist uses the Aristotelian issues in order to foster a ultra-literal reading of the Writ, even though the plain meaning bears contradiction and nonsense. This way of rationalising the irrational also appears through a negative attitude towards metaphor and synonymy and through his struggle for defending etymologies that are often farfetched. Moreover, Caspi frequently reinterprets words of Biblical Hebrew through the mirror of Hebrew philosophical terminology coined after the Arabic pattern. The specificity of Caspi's literal and philosophical approach derives from his effort to combine two kind of logic: the one internal to the commented text or to the Hebrew language and the other external and generic, that of Medieval Aristotelism.